Coupling comes from
nearby sources producing magnetic or electric fields. The biggest source
of inductive and capacitive coupling interference comes from the pulsed
magnet producing a noise signal with a peak in the fournien transform
near 40 Hz (see Magnetic Field Profile). Because our experiments are placed
inside pulsed field magnets, this is always huge and one of the most difficult
to overcome especially in the case of low resistance measurements.

To minimize pulsed
magnet infererence, make sure that the wires connecting instruments do
not have a lot of open-loop area perpendicular to the magnetic field.
Cables should be as short as possible and multiple cables should be held
or twisted together to minimize the loop area. Also, all cables should
be moved as far away as possible from magnetic field sources. This includes
all the cables leading out from the probe to the panel that leads to the
data recording instruments.

60 Hz noise from the
power isolation transformers can also enter the experiment via inductive
coupling, and computer displays (CRT and the backlight of LCD) are strong
sources of capacitively coupled interference.